shell on top of shell

[Mattp]

someone i know told me about how someone he knows puts two shells in a mortar...cuts the bottom shells fuse and lights the upper shells fuse... and they both ignite and shoot out... has anyone ever heard of this.. is this how peanut shells started out??? i do not plan on trying this myself but was very curious if this is a thing??? or is this guy talking s#!t.. sounds plausible to me though,, but i also think the upper shells lift charge may damage the lower shell.. and/or not allow the proper back pressure for it to go up high

[jamisonlm3]

I've heard it called piggybacking before. When the lift of a shell goes off, there's so much fire and heat that it can ignite the timing fuse of a second one. This is how tails on shells work. My understanding is it's not recommended or done with any regularity.

[Bung]

someone i know told me about how someone he knows puts two shells in a mortar...cuts the bottom shells fuse and lights the upper shells fuse... and they both ignite and shoot out... has anyone ever heard of this.. is this how peanut shells started out??? i do not plan on trying this myself but was very curious if this is a thing??? or is this guy talking s#!t.. sounds plausible to me though,, but i also think the upper shells lift charge may damage the lower shell.. and/or not allow the proper back pressure for it to go up high

How it should be, is the lift charge of the bottom shell should provide enough lift for extra weight. The fuse runs to the lift charge, then the timing fuse of the top shell is ignited by the quick match as it burns to the lift charge, then the lift charge ignition ignites the bottom shell timer fuse and then the burst charge is ignited at the desirable height. From how you have worded it, it would result in failure of the bottom shell and a very low burst height of the top shell, so you are right in your view on what would happen. There should only be one lift charge - the bottom shell.

There should be a cross section image of a peanut shell construction here: http://www.pyro2.org.uk/wp-content/uploads/yellowbook.pdf

Scroll down to page 60.

[RalphieJ]

I have seen this done twice during hand-fired shows, and only when the mortars were single-banked in a small show where the bulk of the shells in the body of the show were no larger than 4"-5". When single-banking, you don't have the luxury of another mortar of the same size to switch to, a shell misfired in the 3" pipe. Other sized shells were fired through their sequences a couple of times, omitting the 3", and thus allowing (hopefully!) sufficient time to rule out a hang fire. The lead then dropped another shell on top of the misfire. The blast from it's lift ignited the lift below without penetrating the shell's casing. Both shells were lifted to sufficient height without having any stars hit the ground. I will say that in each occurrence the shells were 3" ball oriental imports (Korean, I seem to recall). Needless to say, double-banking the mortars became the norm going forward.

[Mattp]

How it should be, is the lift charge of the bottom shell should provide enough lift for extra weight. The fuse runs to the lift charge, then the timing fuse of the top shell is ignited by the quick match as it burns to the lift charge, then the lift charge ignition ignites the bottom shell timer fuse and then the burst charge is ignited at the desirable height. From how you have worded it, it would result in failure of the bottom shell and a very low burst height of the top shell, so you are right in your view on what would happen. There should only be one lift charge - the bottom shell.

There should be a cross section image of a peanut shell construction here: http://www.pyro2.org.uk/wp-content/uploads/yellowbook.pdf

Scroll down to page 60.

wow.. thank you,, think i found some new reading material. that is a great document.. very similar to our nfpa documents... and yes.. that makes sense,, more of a peanut shell.. but how this person explained it to me was both shells still had their lift charges

[Mattp]

I have seen this done twice during hand-fired shows, and only when the mortars were single-banked in a small show where the bulk of the shells in the body of the show were no larger than 4"-5". When single-banking, you don't have the luxury of another mortar of the same size to switch to, a shell misfired in the 3" pipe. Other sized shells were fired through their sequences a couple of times, omitting the 3", and thus allowing (hopefully!) sufficient time to rule out a hang fire. The lead then dropped another shell on top of the misfire. The blast from it's lift ignited the lift below without penetrating the shell's casing. Both shells were lifted to sufficient height without having any stars hit the ground. I will say that in each occurrence the shells were 3" ball oriental imports (Korean, I seem to recall). Needless to say, double-banking the mortars became the norm going forward.

thats pretty crazy... but it does work huh!!!